Steel-shell concrete, as a new structural form, is used in the submarine immersed tube tunnel project in the Shenzhen-Zhongshan Link. Construction factors tend to form void between steel and concrete, which affects the overall force performance of the structure. In order to achieve the accurate detection of void defects at the steel-shell concrete interface, this paper takes the immersed tube tunnel in the Shenzhen-Zhongshan Link as the engineering background, the specimens with different void shapes were made, conducted research on the application of impact imaging method in void detection of steel-shell concrete interface. The test results show that the method can better reflect the actual void space distribution at the steel-shell concrete interface, quantitatively evaluate the void condition, the results have important reference significance for the improvement of construction control measures.